Process for making esters of acrylic acid



Patented Mar. 20, 1934 UNITED STATES PROCESS Walter Bauer and Hell Germany, assignors,

FOR. MAKING ESTERS or ACRYLIC ACID muth I auth, Darmstadt,

by mesne assignments, to

Rohm & Haas Company,,Philadelphia,'Pa., a corporation of Delaware No Drawing. Application January 28, 1932, Serial No. 589,528. -In Germany January 29, 1931 17 Claims.

The invention relates to a process for making esters of acrylic acid.

The process, known per se, of making esters Irom acid chlorids and alcohols, heretofore, in the case of acrylic acid chlorid yielded only betachloro-propionic acid esters.

The present invention resides in the discovery that acrylic acid esters may be produced by reacting acrylic acid halides and alcohols or phenols V by cutting down the concentration of the genererated hydrogen halide to such an extent that it no longer has the power to add to the double bond of acrylic acid halide. This may be accomplished r by dilution with non-reactive liquid solvents or by neutralization with weak bases, or by a combination of the two. The diluting agent employed may be either an excess of the alcohol or phenol, or other non-reactive liquid solvents may be employed either alone or incombin'ation with an excess of the alcohol or phenol.

It has been found that acrylic acid esters may be obtained from acrylic acid chloride in the best yield if a great excess of alcohol, about 6 mols, for example, is used for 1 mol of acrylic acid chloride, and/or if the alcohol is suitably diluted with neutral solvents and/or diluting agents, for example, ketones, hydrocarbons, chlorinated hydrocarbons, and then the acrylic acid ester is isolated fromthe reaction product in a known manher. The formation of beta chlcro propionic acid esters is hereby limited to a few per cent. The action of the reacting components upon each other should preferably be so effected that the resulting hydrogen chloride is distributed by the excess of alcoholor the diluting agent used and thus its attachment to the resulting acrylic acid esters prevented. This result may be accomplished, for example, by adding the acrylic acid halide to the alcohol or the mixture of alcohol and diluting agent.

If less than 6 mols of alcohol are used; the proportion of beta-chloro-propionic acid esters increases. It has, however, been found that the yield of acrylic acid esters is increased, if the 5 preparation takes place immediately after the esterification. I

It has furthermore been found that the formation of acrylic acid esters is increased to almost theoretical yield even when using less than 6 mole of alcohol, if, before, or duringthe reaction, agents which will bind (combine with) hydrogen chloride are added. Carbonates and bicarbonates serve excellently for such purpose, and also organic and inorganic bases and salts of weak acids. The transformation is ad Iantageously carried out at a low temperature. However, it is also possible to operate successfully at a high temperature.

Examples I 1. 11 parts by weight oi acrylic acid chloride are treated with 25.6 parts by weight of methanol with cooling. Thereby the methyl ester of acrylic acid is produced to the extent of 96% and betachloro-propionic methyl ester to the extent of 3% of the theoretical amounts. After neutralization the reaction mixture is worked up in known way into acrylic acid ester, and the crude ester is purified by distillation.

2. 11 parts by'weight of acrylic acid chloride are treated with 11 parts by weight of methanol, with cooling. Therebythere results of the theoretical yield of acrylic acid ester in addition to 33%01? the theoretical yield of beta-chloropropionic ester. The working up into acrylic acid ester and the isolation thereof follows in the known way.

3. 11 parts by weight of acrylic acid chloride are added to 10 parts by weight of ethyl alcohol in portions, with cooling, with the simultaneous addition of 10 parts by weight of sodium bicarbonate. The ethyl ester of acrylic acid is produced to the extent of 98% of the theoretical amount; it is isolated in known manner and purified by distillation.

4. 11 parts by weight of acrylic acid chloride are added, with initially moderate cooling, to 12 parts byweight of propyl alcohol with the simultaneous addition of 10 parts by weight of sodium bicarbonate. The propyl ester of acrylic acid is produced to the extent of 96% of the theoretical amount. It is purified after being isolated in the known manner, by distillation.

5. 11 parts by weight of acrylic acid chloride are added to 1'7 parts by weight of amyl alcohol, which are dissolved in 10 parts by weight of acetone, with the simultaneous addition of 10 parts by-weight of sodium bicarbonate. The amyl ester is produced to the extent of 95% of the theoretical yield, and is isolated in known manner and purified by distillation.

6. 10 parts by weight of acrylic acid chloride are added to 11.7 parts by weight of phenol, which are dissolved in- 10 parts by weight of acetone with the addition of 5.7 parts by weight of calcium carbonate, with heating.

Finally, it is heated one-half hour longer on the water bath. The phenyl ester is produced to the extent of 95% of the theoretical yield, and is isolated in known manner and purified by distillation.

7. 10 parts by weight of acrylic acid chloride are added to a solution of 13.5 parts by weight of benzyl alcohol in 15 parts by weight of acetone with the addition of 5.7 parts by weight of calcium carbonate. In order to start the reaction, it is warmed on the water bath, and finally boiled for 20 minutes longer. The benzyl ester of acrylic acid is produced to the extent of approximately 98% of the theoretical amount. It is isolated in known ways and purified by distillation.

9. 11 parts by weight of acrylic acid chloride are transformed with 10 parts by weight of ethyl alcohol, which are dissolved in 20 parts'by weight of benzol, with the simultaneous addition of 6 parts by weight of calcium oxide. The ethyl ester of acrylic acid is produced with a yield of about 90%, and may be purified by washing out and fractionation. I

10. 16 parts by weight of acrylic acid bromide are treated with 11 parts by weight of methanol in which 18 parts by weight of di-ethyl-anilin are dissolved. The methyl ester of acrylic acid is obtained in a yield of from 90-95%.

11. 11 parts by weight of acrylic acid chloride are brought together with 4 parts by weight of methanol, in which 18 parts by weight of diethyl-anilin are dissolved. The yield amounts to about 90%.

It will be understood that the process is applicable to the preparation of acrylic acid esters from acrylic acid halids generally and alcohols or phenols, although acrylic acid chlorides are of particular commercial importance. It will also be understood that by the term alcohols as used in the present specification it is intended to cover monoor polyhydric aromatic and aliphatic alcohols. The term phenols is understood to mean aromatic compounds having hydroxyl groups attached to nuclear carbon atoms.

It is an important feature of the present invention that the reacting products be employed in sufficient dilution. The alcohol itself may be used as a, diluting agent and the other diluting agents available for use should be as indifferent as possible with respect to the halide of the acrylic acid.

In addition to the solvents already mentioned as suitable diluting agents, many other materials may be employed as diluting agents; such as, benzine (gasoline) for example, benzol, tetralin, carbon tetrachloride, ethylene chloride, chlorobenzol; ketones such as acetone, methyl-ethylketone, etc? In fact, practically all neutral or non-reactive liquids may be employed as diluting agents.

Where the alcohol is employed in concentrated condition, diluting agents or bases or both are added in order 'to'attain the desired dilution.

[It will be noted from the foregoing examples that where neutral liquids are employed as diluting agents in the absence of an excess of al-- cohol or of acid-binding agents, the quantity by weight of such diluting agent should be at least equal to the quantity of theacrylic acid halide undergoing reaction. Where the diluting agent is used in conjunction with an excess of alcohol or with an acid-binding agent, thequantity of the diluting agent may be reduced.

What we claim is: e

1. The improvement in the process of reacting an acrylic acid halide with a member of a group consisting of alcohols and phenols which comprises producing acrylic acid esters by cutting down the concentration of the generated hydrogen halide to such an extent that it no longer has .the power to add to the double bond of acrylic acid halide.

2. In the process as set forth in claim 1, the improvement which consists in cutting down the concentration of the generated hydrogen halide by dilution with non-reactive liquid solvents.

3. In,the process as set forth in claim 1, the improvement which comprises cutting down the concentration of the generated hydrogen halide by neutralization-with weak bases.

4. A process of producing esters of acrylic acid which comprises reacting an acrylic acid halide with a member of a group consisting of alcohols and phenols, in the presence of a. non-reactive liquid diluting'agent.

5. A process of producing esters of acrylic acid as set forth in-claim 4, in which both an excess of alcohol or phenol and a diluting agent other than alcohol or phenol are employed.

6. A process of producing esters of acrylic acid 1 which comprises reacting an acrylic acid halide with a member of a group consisting of alcohols and phenols, the alcohols or phenols being used insubstantial excess ofthe theoretical quantity required for reaction. I

.7. A process of producing esters of acrylic acid which comprises reacting an acrylic acid halide with a member of a group consisting of alcohols and phenols in the presence of a non-reacting liquid diluting agent other than alcohols or phenols.

8. A process as set forth in claim 4' wherein the halide undergoing reaction is the chloride of acrylic acid.

9. A process as set forth in claim 4 wherein not less than six mols of alcohol are employed for each mol of the acrylic acid halide undergoing reaction.

10. A process as set forth in claim 4 wherein the halide undergoing reaction isthe chloride of acrylic acid and not less than six mols of an alcohol is employed for each mol of acrylic acid chloride.

11. A process of producing esters of acrylic acid which comprises reacting an acrylic acid halide with a member of a group which consists of alcohols and phenols, in the presence of a non-reactive liquid diluting agent selected from a group which consists of hydrocarbons, chlorinated hydrocarbons, and ketones, the quantity of the diluting agent employed being at least equal by weight to the weight of the acrylic acid halide. v

12. A process as set forth in claim 11 in which acrylic acid chloride is the halide undergoing reaction.

13. A process as set forth in claim 11 in which the acrylic acid halide is reacted with a phenol.

14. A process as set forth in claim 11 in which the diluting agent is acetone.

15. A process as set forth in claim 4 wherein both a non-reacting liquid diluting agent and an acid-binding agent are employed.

16. A process as set forth in claim 4 wherein- 

